Timothy got a job working for a political candidate who was running for mayor. He decided to apply his knowledge about experiments in his new job and test whether the method of distributing campaign literature caused more people to vote for a candidate. He distributed campaign literature about the candidate to the Riverdale neighborhood in a bright blue envelope that a volunteer hand-placed in each person's front door. He distributed the same campaign literature about the candidate to the Golfview neighborhood by mailing it in a plain white envelope that went to each address. He later learned that Riverdale was a low-income area of the city that was almost entirely Latino and was 95% Catholic. Golfview was a mostly upper-income area in the city and its residents were 100% white Protestants. What problem with internal validity might threaten his ability to trust the experimental results?

Question

Quizplus · Accepted Answer

The problem with internal validity in this scenario is selection bias. Timothy's experiment used two different neighborhoods with significantly different demographic characteristics (income level, ethnicity, and religion) to test the effectiveness of campaign literature distribution methods. This means the groups were not equivalent at the start of the experiment, which could influence the outcome independently of the distribution method, thus threatening the internal validity of the experiment's results.

Timothy Got a Job Working for a Political Candidate Who